The present invention relates to a gear train in which two or more rolls, wheels, drums, etc., are arranged in side-by-side relation and along a common axis for independent rotation thereon, and wherein respective two such rolls are coupled by a transfer pinion.
Gearing of the type outlined above is used, for example, to interconnect the digit or cipher rolls of a mechanical counter. The digits are, e.g., printed on the periphery of the drums or rolls. In such a counter, the different rolls represent, e.g., different decades. The unit roll will transfer one angular unit step to the tens-roll after on revolution of the unit roll. After one revolution of the tens-roll, an (angular) unit step is transferred to the hundreds roll, etc. The transfer is effected in either case by transfer pinions. The latter are being disengaged from all drums or rolls for resetting the counter.
These counters are specifically constructed in that the pinion is always in engagement with teeth, pins or the like on the respective transferee roll (or the transfer-receiving side of a roll), while the pinion is only temporarily in driving engagement with the transferor roll, namely whenever the latter has completed one revolution. Of course, most rolls act as transferee rolls on one side, and as transferor roll on the other side, there being two different pinions involved accordingly as to each such roll. The roll acting occasionally as transferor roll is for most of its rotation freely rotatable. The transferor side of a roll has, for example, just two teeth to obtain a stepwise rotational transfer step for each completed revolution, while being disengaged from the transfer pinion on that side for most of a full turn.
These rolls or drums are constructed in that the teeth or pins on the transferor side of one roll axially face the teeth or pins on the transferee side of another roll, and the transfer pinion whenever engaging the transferor side pins turns the other roll. The two rolls are axially spaced apart so that pins facing each other axially have sufficient clearance space between them. The space between the rolls is, therefore, at last as large as the sum of the axial lengths of facing pins. The same conditions arise in all of these kinds of gears irrespective of their use. In the case of a counter, the rolls carry ciphers along their periphery which must have a reasonable size for being legible. In the case of an automated counter readout the dimensions of the printed-on ciphers are fixed. This holds true particularly with regard to the width of the characters. According, the axial width of such cipher rolls is more or less a given parameter, and the spacing between adjacent cipher rolls is determined by the transfer construction outlined above. This in turn establishes a particular axial length for a particular counter capacity. It has found that occasionally these conditions have operated as a constraint that cannot be met if mounting space and counter capacity are also given parameters. Such a constraint has been encountered, for example, in telephone charge counters.